The invention relates to a seat, particularly a vehicle seat, and preferably an aircraft passenger seat, with a seat element and a seat element support, a backrest whose tilt angle can be adjusted, and at least one armrest, whereby said armrest is mounted in such a way as to swivel at the backrest, whereby, as the tilt angle of the backrest increases or decreases, the armrest is continuously carried along with it by an adjustment mechanism, and whereby the adjustment mechanism for the armrest has at least four articulation points, of which one is located in the seat element support and the other in a connecting-rod part and, of the other two articulation points, one moves together with the connecting-rod part and the other with the backrest.
DE 197 24 763 A1 discloses a vehicle seat, especially an aircraft passenger seat, with a tilt-adjustment device, by means of which the backrest is able to swivel around a swivel axis relative to the seat element. Owing to the fact that the position of the swivel axis is moved by a lever drive from an area between the backrest and the seat element in such a way that the swivel axis is located at the level of the seat occupant""s hips, relative movement between the backrest, on the one hand, and the seat occupant""s back, on the other, is avoided, so that the so-called shirt-ride-up effect cannot arise when the backrest is tilted to the rear. The vehicle seat designed for this purpose has a high degree of seating comfort; however, the armrests on both sides of the seat are kept in an essentially horizontal position, which adversely affects the seat occupant""s seating comfort, especially when the backrest is tilted far back. Accordingly, it would be desirable to make it possible to adjust the armrests as well.
The state of the art provides suggestions for how to adjust the armrest or arm support. Thus, for example, DE 196 12 287 C1 relates to a seat device, especially a therapy seat with a seat surface and a backrest whose tilt angle can be adjusted. Moreover, the disclosed seat has at least one armrest that consists of an upper support part and a lower guide part, whereby the support part can swivel around a horizontal axis that is located on one side of the backrest and is detachably attached to this axis. Moreover, the guide part of the armrest can slide along a fixed guide and in this connection is designed in such a form that, when it swivels around the axis, the support part executes a translational motion that is determined by the involute shape of the guide part. Owing to this forced mechanical connection, during the entire time that the seat-back tilt angle is being adjusted, the arm support of the corresponding armrest is in a horizontal, continuously lowering position that occurs when moving from a sitting to a reclining position. If, however, the backrest is not completely in the horizontal position, a seat occupant finds it uncomfortable to have to keep his arms in a horizontal position on the arm supports when the backrest is partially tilted to the rear.
Similar considerations also apply to the arm supports described in DE 43 10 454 C1 and DE 195 42 198 A1, in which the arm support can be shifted from an unused position to a position of use by means of swiveling parallelogram guide rods, whereby in the position of use the arm support can be moved up and down in an essentially horizontal position regardless of the tilt angle of the backrest.
DE 38 14 758 A1 discloses a vehicle seat with a seat element, whereby the lateral spars of a backrest are flexibly connected to the frame of a seat element by means of a swivel axis. With the known approach, above the swivel axis each seat lateral spar has a pivot above the swivel axis, where an armrest is rotatably mounted that is connected to a guide rod attached to the seat element, forming a parallelogram-shaped support. In this way, regardless of the tilt angle of the backrest, the arm support is held in a position parallel to the seat element, whereby, when the backrest moves as the angle of tilt is adjusted, the armrest is carried with it to the rear as it descends, thereby hampering the occupant""s ability to rest his arms on a support. Moreover, the known approach requires a large number of connecting rods that are controlled by a rotating armature; this disclosed approach results in a heavy structure, and therefore to date it has been successfully implemented only in motor vehicles.
On the basis of this state of the art the object of the invention is to develop a seat, especially an aircraft passenger seat, that meets even elevated comfort requirements, especially for cases where the backrest is in a partially tilted-back position that is located between an upright seat position and a reclined position that is, if possible, largely horizontal. Moreover, the desired solution should be compact and lightweight. A seat with the features of claim 1 in its entirety accomplishes this object.
In that, as specified in the characterizing part of claim 1, the one articulation point of the connecting-rod part that is fixed with regard to the seat element support and the other movable articulation point are located respectively at the opposite ends of the connecting-rod part, in that the movable articulation point of the connecting-rod part forms a guide for the armrest, in that in the area of the fixed articulation point of the connecting-rod part a control part catches it with its one free end and with the fifth articulation point, in that the control part catches the backrest with its other free end by means of another, sixth articulation point, and in that, with the backrest adjusted to any tilted position, the sixth articulation point, by means of which the armrest is swivel-connected to the backrest, remains below the fourth articulation point, a parallelogram-shaped guide for the armrest is provided, whereby it can be lowered on its own, and, if the backrest is to be moved to a virtually completely reclined position in which the above-mentioned parallelogram geometrically follows an imaginary line when the backrest is tilted halfway to the rear by virtue of the fact that the four articulation points of the parallelogram lie on the same line, an appropriate critical dead-center position is easily overcome by virtue of the fact that the control part with its other articulation points forms a kind of auxiliary parallelogram which, with the first parallelogram in the above-mentioned dead-center position with its four articulation points, stays in the xe2x80x9ctensionedxe2x80x9d position.
In addition to unhampered operation, the armrest retains its position relative to the tilting motion of the backrest viewed more or less in the longitudinal direction and tilts appreciably only when the backrest is tilted further back, so that the entire armrest area continues to remain available to a seat occupant even in the reclined position. Because of the small number of components required, the approach according to the invention is cost-effective and light in weight, which is of particular importance in aviation in connection with controlling fuel costs. Since, in addition, the essential parts of the adjustment parallelogram are located in the area of the seat element support, there are no mechanical components of an adjustment device in the area of the seat element or the backrest; particularly in the event of a crash, this provides for enhanced safety since the seat occupant cannot be injured by such mechanical components.
It is preferable that provision is made such that, with the backrest in the upright position, the arm support of the armrest is essentially horizontal or is tilted only slightly from the horizontal and that, with the backrest tilted all the way to the rear, the arm support is essentially parallel to the backrest. Thus, even when the aircraft passenger seat is in the reclined or berthed position, it is possible for the seat occupant to hold his arms in a relaxed position; in this case, in keeping with improved seating comfort, the occupant""s arms are essentially in the same plane as his torso.
Other advantageous embodiments are features of the other dependent claims.
Below, the seat according to the invention is explained in greater detail using a sample embodiment in the nature of an aircraft passenger seat.